drivers/firmware/efi/efi-pstore.c - kernel/msm-4.9 - Gitiles

 #include <linux/efi.h>
 #include <linux/module.h>
 #include <linux/pstore.h>
 #include <linux/slab.h>
 #include <linux/ucs2_string.h>

 #define DUMP_NAME_LEN 52

 static bool efivars_pstore_disable =
 	IS_ENABLED(CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE);

 module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644);

 #define PSTORE_EFI_ATTRIBUTES \
 	(EFI_VARIABLE_NON_VOLATILE | \
 	 EFI_VARIABLE_BOOTSERVICE_ACCESS | \
 	 EFI_VARIABLE_RUNTIME_ACCESS)

 static int efi_pstore_open(struct pstore_info *psi)
 {
 	psi->data = NULL;
 	return 0;
 }

 static int efi_pstore_close(struct pstore_info *psi)
 {
 	psi->data = NULL;
 	return 0;
 }

 struct pstore_read_data {
 	u64 *id;
 	enum pstore_type_id *type;
 	int *count;
 	struct timespec *timespec;
 	bool *compressed;
 	ssize_t *ecc_notice_size;
 	char **buf;
 };

 static inline u64 generic_id(unsigned long timestamp,
 			     unsigned int part, int count)
 {
 	return ((u64) timestamp * 100 + part) * 1000 + count;
 }

 static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
 {
 	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 	struct pstore_read_data *cb_data = data;
 	char name[DUMP_NAME_LEN], data_type;
 	int i;
 	int cnt;
 	unsigned int part;
 	unsigned long time, size;

 	if (efi_guidcmp(entry->var.VendorGuid, vendor))
 		return 0;

 	for (i = 0; i < DUMP_NAME_LEN; i++)
 		name[i] = entry->var.VariableName[i];

 	if (sscanf(name, "dump-type%u-%u-%d-%lu-%c",
 		   cb_data->type, &part, &cnt, &time, &data_type) == 5) {
 		*cb_data->id = generic_id(time, part, cnt);
 		*cb_data->count = cnt;
 		cb_data->timespec->tv_sec = time;
 		cb_data->timespec->tv_nsec = 0;
 		if (data_type == 'C')
 			*cb_data->compressed = true;
 		else
 			*cb_data->compressed = false;
 		*cb_data->ecc_notice_size = 0;
 	} else if (sscanf(name, "dump-type%u-%u-%d-%lu",
 		   cb_data->type, &part, &cnt, &time) == 4) {
 		*cb_data->id = generic_id(time, part, cnt);
 		*cb_data->count = cnt;
 		cb_data->timespec->tv_sec = time;
 		cb_data->timespec->tv_nsec = 0;
 		*cb_data->compressed = false;
 		*cb_data->ecc_notice_size = 0;
 	} else if (sscanf(name, "dump-type%u-%u-%lu",
 			  cb_data->type, &part, &time) == 3) {
 		/*
 		 * Check if an old format,
 		 * which doesn't support holding
 		 * multiple logs, remains.
 		 */
 		*cb_data->id = generic_id(time, part, 0);
 		*cb_data->count = 0;
 		cb_data->timespec->tv_sec = time;
 		cb_data->timespec->tv_nsec = 0;
 		*cb_data->compressed = false;
 		*cb_data->ecc_notice_size = 0;
 	} else
 		return 0;

 	entry->var.DataSize = 1024;
 	__efivar_entry_get(entry, &entry->var.Attributes,
 			   &entry->var.DataSize, entry->var.Data);
 	size = entry->var.DataSize;
 	memcpy(*cb_data->buf, entry->var.Data,
 	       (size_t)min_t(unsigned long, EFIVARS_DATA_SIZE_MAX, size));

 	return size;
 }

 /**
  * efi_pstore_scan_sysfs_enter
  * @pos: scanning entry
  * @next: next entry
  * @head: list head
  */
 static void efi_pstore_scan_sysfs_enter(struct efivar_entry *pos,
 					struct efivar_entry *next,
 					struct list_head *head)
 {
 	pos->scanning = true;
 	if (&next->list != head)
 		next->scanning = true;
 }

 /**
  * __efi_pstore_scan_sysfs_exit
  * @entry: deleting entry
  * @turn_off_scanning: Check if a scanning flag should be turned off
  */
 static inline void __efi_pstore_scan_sysfs_exit(struct efivar_entry *entry,
 						bool turn_off_scanning)
 {
 	if (entry->deleting) {
 		list_del(&entry->list);
 		efivar_entry_iter_end();
 		efivar_unregister(entry);
 		efivar_entry_iter_begin();
 	} else if (turn_off_scanning)
 		entry->scanning = false;
 }

 /**
  * efi_pstore_scan_sysfs_exit
  * @pos: scanning entry
  * @next: next entry
  * @head: list head
  * @stop: a flag checking if scanning will stop
  */
 static void efi_pstore_scan_sysfs_exit(struct efivar_entry *pos,
 				       struct efivar_entry *next,
 				       struct list_head *head, bool stop)
 {
 	__efi_pstore_scan_sysfs_exit(pos, true);
 	if (stop)
 		__efi_pstore_scan_sysfs_exit(next, &next->list != head);
 }

 /**
  * efi_pstore_sysfs_entry_iter
  *
  * @data: function-specific data to pass to callback
  * @pos: entry to begin iterating from
  *
  * You MUST call efivar_enter_iter_begin() before this function, and
  * efivar_entry_iter_end() afterwards.
  *
  * It is possible to begin iteration from an arbitrary entry within
  * the list by passing @pos. @pos is updated on return to point to
  * the next entry of the last one passed to efi_pstore_read_func().
  * To begin iterating from the beginning of the list @pos must be %NULL.
  */
 static int efi_pstore_sysfs_entry_iter(void *data, struct efivar_entry **pos)
 {
 	struct efivar_entry *entry, *n;
 	struct list_head *head = &efivar_sysfs_list;
 	int size = 0;

 	if (!*pos) {
 		list_for_each_entry_safe(entry, n, head, list) {
 			efi_pstore_scan_sysfs_enter(entry, n, head);

 			size = efi_pstore_read_func(entry, data);
 			efi_pstore_scan_sysfs_exit(entry, n, head, size < 0);
 			if (size)
 				break;
 		}
 		*pos = n;
 		return size;
 	}

 	list_for_each_entry_safe_from((*pos), n, head, list) {
 		efi_pstore_scan_sysfs_enter((*pos), n, head);

 		size = efi_pstore_read_func((*pos), data);
 		efi_pstore_scan_sysfs_exit((*pos), n, head, size < 0);
 		if (size)
 			break;
 	}
 	*pos = n;
 	return size;
 }

 /**
  * efi_pstore_read
  *
  * This function returns a size of NVRAM entry logged via efi_pstore_write().
  * The meaning and behavior of efi_pstore/pstore are as below.
  *
  * size > 0: Got data of an entry logged via efi_pstore_write() successfully,
  *           and pstore filesystem will continue reading subsequent entries.
  * size == 0: Entry was not logged via efi_pstore_write(),
  *            and efi_pstore driver will continue reading subsequent entries.
  * size < 0: Failed to get data of entry logging via efi_pstore_write(),
  *           and pstore will stop reading entry.
  */
 static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
 			       int *count, struct timespec *timespec,
 			       char **buf, bool *compressed,
 			       ssize_t *ecc_notice_size,
 			       struct pstore_info *psi)
 {
 	struct pstore_read_data data;
 	ssize_t size;

 	data.id = id;
 	data.type = type;
 	data.count = count;
 	data.timespec = timespec;
 	data.compressed = compressed;
 	data.ecc_notice_size = ecc_notice_size;
 	data.buf = buf;

 	*data.buf = kzalloc(EFIVARS_DATA_SIZE_MAX, GFP_KERNEL);
 	if (!*data.buf)
 		return -ENOMEM;

 	efivar_entry_iter_begin();
 	size = efi_pstore_sysfs_entry_iter(&data,
 					   (struct efivar_entry **)&psi->data);
 	efivar_entry_iter_end();
 	if (size <= 0)
 		kfree(*data.buf);
 	return size;
 }

 static int efi_pstore_write(enum pstore_type_id type,
 		enum kmsg_dump_reason reason, u64 *id,
 		unsigned int part, int count, bool compressed, size_t size,
 		struct pstore_info *psi)
 {
 	char name[DUMP_NAME_LEN];
 	efi_char16_t efi_name[DUMP_NAME_LEN];
 	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 	int i, ret = 0;

 	sprintf(name, "dump-type%u-%u-%d-%lu-%c", type, part, count,
 		get_seconds(), compressed ? 'C' : 'D');

 	for (i = 0; i < DUMP_NAME_LEN; i++)
 		efi_name[i] = name[i];

 	efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES,
 			      !pstore_cannot_block_path(reason),
 			      size, psi->buf);

 	if (reason == KMSG_DUMP_OOPS)
 		efivar_run_worker();

 	*id = part;
 	return ret;
 };

 struct pstore_erase_data {
 	u64 id;
 	enum pstore_type_id type;
 	int count;
 	struct timespec time;
 	efi_char16_t *name;
 };

 /*
  * Clean up an entry with the same name
  */
 static int efi_pstore_erase_func(struct efivar_entry *entry, void *data)
 {
 	struct pstore_erase_data *ed = data;
 	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 	efi_char16_t efi_name_old[DUMP_NAME_LEN];
 	efi_char16_t *efi_name = ed->name;
 	unsigned long ucs2_len = ucs2_strlen(ed->name);
 	char name_old[DUMP_NAME_LEN];
 	int i;

 	if (efi_guidcmp(entry->var.VendorGuid, vendor))
 		return 0;

 	if (ucs2_strncmp(entry->var.VariableName,
 			  efi_name, (size_t)ucs2_len)) {
 		/*
 		 * Check if an old format, which doesn't support
 		 * holding multiple logs, remains.
 		 */
 		sprintf(name_old, "dump-type%u-%u-%lu", ed->type,
 			(unsigned int)ed->id, ed->time.tv_sec);

 		for (i = 0; i < DUMP_NAME_LEN; i++)
 			efi_name_old[i] = name_old[i];

 		if (ucs2_strncmp(entry->var.VariableName, efi_name_old,
 				  ucs2_strlen(efi_name_old)))
 			return 0;
 	}

 	if (entry->scanning) {
 		/*
 		 * Skip deletion because this entry will be deleted
 		 * after scanning is completed.
 		 */
 		entry->deleting = true;
 	} else
 		list_del(&entry->list);

 	/* found */
 	__efivar_entry_delete(entry);

 	return 1;
 }

 static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
 			    struct timespec time, struct pstore_info *psi)
 {
 	struct pstore_erase_data edata;
 	struct efivar_entry *entry = NULL;
 	char name[DUMP_NAME_LEN];
 	efi_char16_t efi_name[DUMP_NAME_LEN];
 	int found, i;
 	unsigned int part;

 	do_div(id, 1000);
 	part = do_div(id, 100);
 	sprintf(name, "dump-type%u-%u-%d-%lu", type, part, count, time.tv_sec);

 	for (i = 0; i < DUMP_NAME_LEN; i++)
 		efi_name[i] = name[i];

 	edata.id = part;
 	edata.type = type;
 	edata.count = count;
 	edata.time = time;
 	edata.name = efi_name;

 	efivar_entry_iter_begin();
 	found = __efivar_entry_iter(efi_pstore_erase_func, &efivar_sysfs_list, &edata, &entry);

 	if (found && !entry->scanning) {
 		efivar_entry_iter_end();
 		efivar_unregister(entry);
 	} else
 		efivar_entry_iter_end();

 	return 0;
 }

 static struct pstore_info efi_pstore_info = {
 	.owner		= THIS_MODULE,
 	.name		= "efi",
 	.flags		= PSTORE_FLAGS_FRAGILE,
 	.open		= efi_pstore_open,
 	.close		= efi_pstore_close,
 	.read		= efi_pstore_read,
 	.write		= efi_pstore_write,
 	.erase		= efi_pstore_erase,
 };

 static __init int efivars_pstore_init(void)
 {
 	if (!efi_enabled(EFI_RUNTIME_SERVICES))
 		return 0;

 	if (!efivars_kobject())
 		return 0;

 	if (efivars_pstore_disable)
 		return 0;

 	efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
 	if (!efi_pstore_info.buf)
 		return -ENOMEM;

 	efi_pstore_info.bufsize = 1024;
 	spin_lock_init(&efi_pstore_info.buf_lock);

 	if (pstore_register(&efi_pstore_info)) {
 		kfree(efi_pstore_info.buf);
 		efi_pstore_info.buf = NULL;
 		efi_pstore_info.bufsize = 0;
 	}

 	return 0;
 }

 static __exit void efivars_pstore_exit(void)
 {
 	if (!efi_pstore_info.bufsize)
 		return;

 	pstore_unregister(&efi_pstore_info);
 	kfree(efi_pstore_info.buf);
 	efi_pstore_info.buf = NULL;
 	efi_pstore_info.bufsize = 0;
 }

 module_init(efivars_pstore_init);
 module_exit(efivars_pstore_exit);

 MODULE_DESCRIPTION("EFI variable backend for pstore");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:efivars");
	#include <linux/efi.h>
	#include <linux/module.h>
	#include <linux/pstore.h>
	#include <linux/slab.h>
	#include <linux/ucs2_string.h>

	#define DUMP_NAME_LEN 52

	static bool efivars_pstore_disable =
	IS_ENABLED(CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE);

	module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644);

	#define PSTORE_EFI_ATTRIBUTES \
	(EFI_VARIABLE_NON_VOLATILE \| \
	EFI_VARIABLE_BOOTSERVICE_ACCESS \| \
	EFI_VARIABLE_RUNTIME_ACCESS)

	static int efi_pstore_open(struct pstore_info *psi)
	{
	psi->data = NULL;
	return 0;
	}

	static int efi_pstore_close(struct pstore_info *psi)
	{
	psi->data = NULL;
	return 0;
	}

	struct pstore_read_data {
	u64 *id;
	enum pstore_type_id *type;
	int *count;
	struct timespec *timespec;
	bool *compressed;
	ssize_t *ecc_notice_size;
	char **buf;
	};

	static inline u64 generic_id(unsigned long timestamp,
	unsigned int part, int count)
	{
	return ((u64) timestamp * 100 + part) * 1000 + count;
	}

	static int efi_pstore_read_func(struct efivar_entry entry, void data)
	{
	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
	struct pstore_read_data *cb_data = data;
	char name[DUMP_NAME_LEN], data_type;
	int i;
	int cnt;
	unsigned int part;
	unsigned long time, size;

	if (efi_guidcmp(entry->var.VendorGuid, vendor))
	return 0;

	for (i = 0; i < DUMP_NAME_LEN; i++)
	name[i] = entry->var.VariableName[i];

	if (sscanf(name, "dump-type%u-%u-%d-%lu-%c",
	cb_data->type, &part, &cnt, &time, &data_type) == 5) {
	*cb_data->id = generic_id(time, part, cnt);
	*cb_data->count = cnt;
	cb_data->timespec->tv_sec = time;
	cb_data->timespec->tv_nsec = 0;
	if (data_type == 'C')
	*cb_data->compressed = true;
	else
	*cb_data->compressed = false;
	*cb_data->ecc_notice_size = 0;
	} else if (sscanf(name, "dump-type%u-%u-%d-%lu",
	cb_data->type, &part, &cnt, &time) == 4) {
	*cb_data->id = generic_id(time, part, cnt);
	*cb_data->count = cnt;
	cb_data->timespec->tv_sec = time;
	cb_data->timespec->tv_nsec = 0;
	*cb_data->compressed = false;
	*cb_data->ecc_notice_size = 0;
	} else if (sscanf(name, "dump-type%u-%u-%lu",
	cb_data->type, &part, &time) == 3) {
	/*
	* Check if an old format,
	* which doesn't support holding
	* multiple logs, remains.
	*/
	*cb_data->id = generic_id(time, part, 0);
	*cb_data->count = 0;
	cb_data->timespec->tv_sec = time;
	cb_data->timespec->tv_nsec = 0;
	*cb_data->compressed = false;
	*cb_data->ecc_notice_size = 0;
	} else
	return 0;

	entry->var.DataSize = 1024;
	__efivar_entry_get(entry, &entry->var.Attributes,
	&entry->var.DataSize, entry->var.Data);
	size = entry->var.DataSize;
	memcpy(*cb_data->buf, entry->var.Data,
	(size_t)min_t(unsigned long, EFIVARS_DATA_SIZE_MAX, size));

	return size;
	}

	/**
	* efi_pstore_scan_sysfs_enter
	* @pos: scanning entry
	* @next: next entry
	* @head: list head
	*/
	static void efi_pstore_scan_sysfs_enter(struct efivar_entry *pos,
	struct efivar_entry *next,
	struct list_head *head)
	{
	pos->scanning = true;
	if (&next->list != head)
	next->scanning = true;
	}

	/**
	* __efi_pstore_scan_sysfs_exit
	* @entry: deleting entry
	* @turn_off_scanning: Check if a scanning flag should be turned off
	*/
	static inline void __efi_pstore_scan_sysfs_exit(struct efivar_entry *entry,
	bool turn_off_scanning)
	{
	if (entry->deleting) {
	list_del(&entry->list);
	efivar_entry_iter_end();
	efivar_unregister(entry);
	efivar_entry_iter_begin();
	} else if (turn_off_scanning)
	entry->scanning = false;
	}

	/**
	* efi_pstore_scan_sysfs_exit
	* @pos: scanning entry
	* @next: next entry
	* @head: list head
	* @stop: a flag checking if scanning will stop
	*/
	static void efi_pstore_scan_sysfs_exit(struct efivar_entry *pos,
	struct efivar_entry *next,
	struct list_head *head, bool stop)
	{
	__efi_pstore_scan_sysfs_exit(pos, true);
	if (stop)
	__efi_pstore_scan_sysfs_exit(next, &next->list != head);
	}

	/**
	* efi_pstore_sysfs_entry_iter
	*
	* @data: function-specific data to pass to callback
	* @pos: entry to begin iterating from
	*
	* You MUST call efivar_enter_iter_begin() before this function, and
	* efivar_entry_iter_end() afterwards.
	*
	* It is possible to begin iteration from an arbitrary entry within
	* the list by passing @pos. @pos is updated on return to point to
	* the next entry of the last one passed to efi_pstore_read_func().
	* To begin iterating from the beginning of the list @pos must be %NULL.
	*/
	static int efi_pstore_sysfs_entry_iter(void data, struct efivar_entry *pos)
	{
	struct efivar_entry entry, n;
	struct list_head *head = &efivar_sysfs_list;
	int size = 0;

	if (!*pos) {
	list_for_each_entry_safe(entry, n, head, list) {
	efi_pstore_scan_sysfs_enter(entry, n, head);

	size = efi_pstore_read_func(entry, data);
	efi_pstore_scan_sysfs_exit(entry, n, head, size < 0);
	if (size)
	break;
	}
	*pos = n;
	return size;
	}

	list_for_each_entry_safe_from((*pos), n, head, list) {
	efi_pstore_scan_sysfs_enter((*pos), n, head);

	size = efi_pstore_read_func((*pos), data);
	efi_pstore_scan_sysfs_exit((*pos), n, head, size < 0);
	if (size)
	break;
	}
	*pos = n;
	return size;
	}

	/**
	* efi_pstore_read
	*
	* This function returns a size of NVRAM entry logged via efi_pstore_write().
	* The meaning and behavior of efi_pstore/pstore are as below.
	*
	* size > 0: Got data of an entry logged via efi_pstore_write() successfully,
	* and pstore filesystem will continue reading subsequent entries.
	* size == 0: Entry was not logged via efi_pstore_write(),
	* and efi_pstore driver will continue reading subsequent entries.
	* size < 0: Failed to get data of entry logging via efi_pstore_write(),
	* and pstore will stop reading entry.
	*/
	static ssize_t efi_pstore_read(u64 id, enum pstore_type_id type,
	int count, struct timespec timespec,
	char *buf, bool compressed,
	ssize_t *ecc_notice_size,
	struct pstore_info *psi)
	{
	struct pstore_read_data data;
	ssize_t size;

	data.id = id;
	data.type = type;
	data.count = count;
	data.timespec = timespec;
	data.compressed = compressed;
	data.ecc_notice_size = ecc_notice_size;
	data.buf = buf;

	*data.buf = kzalloc(EFIVARS_DATA_SIZE_MAX, GFP_KERNEL);
	if (!*data.buf)
	return -ENOMEM;

	efivar_entry_iter_begin();
	size = efi_pstore_sysfs_entry_iter(&data,
	(struct efivar_entry **)&psi->data);
	efivar_entry_iter_end();
	if (size <= 0)
	kfree(*data.buf);
	return size;
	}

	static int efi_pstore_write(enum pstore_type_id type,
	enum kmsg_dump_reason reason, u64 *id,
	unsigned int part, int count, bool compressed, size_t size,
	struct pstore_info *psi)
	{
	char name[DUMP_NAME_LEN];
	efi_char16_t efi_name[DUMP_NAME_LEN];
	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
	int i, ret = 0;

	sprintf(name, "dump-type%u-%u-%d-%lu-%c", type, part, count,
	get_seconds(), compressed ? 'C' : 'D');

	for (i = 0; i < DUMP_NAME_LEN; i++)
	efi_name[i] = name[i];

	efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES,
	!pstore_cannot_block_path(reason),
	size, psi->buf);

	if (reason == KMSG_DUMP_OOPS)
	efivar_run_worker();

	*id = part;
	return ret;
	};

	struct pstore_erase_data {
	u64 id;
	enum pstore_type_id type;
	int count;
	struct timespec time;
	efi_char16_t *name;
	};

	/*
	* Clean up an entry with the same name
	*/
	static int efi_pstore_erase_func(struct efivar_entry entry, void data)
	{
	struct pstore_erase_data *ed = data;
	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
	efi_char16_t efi_name_old[DUMP_NAME_LEN];
	efi_char16_t *efi_name = ed->name;
	unsigned long ucs2_len = ucs2_strlen(ed->name);
	char name_old[DUMP_NAME_LEN];
	int i;

	if (efi_guidcmp(entry->var.VendorGuid, vendor))
	return 0;

	if (ucs2_strncmp(entry->var.VariableName,
	efi_name, (size_t)ucs2_len)) {
	/*
	* Check if an old format, which doesn't support
	* holding multiple logs, remains.
	*/
	sprintf(name_old, "dump-type%u-%u-%lu", ed->type,
	(unsigned int)ed->id, ed->time.tv_sec);

	for (i = 0; i < DUMP_NAME_LEN; i++)
	efi_name_old[i] = name_old[i];

	if (ucs2_strncmp(entry->var.VariableName, efi_name_old,
	ucs2_strlen(efi_name_old)))
	return 0;
	}

	if (entry->scanning) {
	/*
	* Skip deletion because this entry will be deleted
	* after scanning is completed.
	*/
	entry->deleting = true;
	} else
	list_del(&entry->list);

	/* found */
	__efivar_entry_delete(entry);

	return 1;
	}

	static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
	struct timespec time, struct pstore_info *psi)
	{
	struct pstore_erase_data edata;
	struct efivar_entry *entry = NULL;
	char name[DUMP_NAME_LEN];
	efi_char16_t efi_name[DUMP_NAME_LEN];
	int found, i;
	unsigned int part;

	do_div(id, 1000);
	part = do_div(id, 100);
	sprintf(name, "dump-type%u-%u-%d-%lu", type, part, count, time.tv_sec);

	for (i = 0; i < DUMP_NAME_LEN; i++)
	efi_name[i] = name[i];

	edata.id = part;
	edata.type = type;
	edata.count = count;
	edata.time = time;
	edata.name = efi_name;

	efivar_entry_iter_begin();
	found = __efivar_entry_iter(efi_pstore_erase_func, &efivar_sysfs_list, &edata, &entry);

	if (found && !entry->scanning) {
	efivar_entry_iter_end();
	efivar_unregister(entry);
	} else
	efivar_entry_iter_end();

	return 0;
	}

	static struct pstore_info efi_pstore_info = {
	.owner = THIS_MODULE,
	.name = "efi",
	.flags = PSTORE_FLAGS_FRAGILE,
	.open = efi_pstore_open,
	.close = efi_pstore_close,
	.read = efi_pstore_read,
	.write = efi_pstore_write,
	.erase = efi_pstore_erase,
	};

	static __init int efivars_pstore_init(void)
	{
	if (!efi_enabled(EFI_RUNTIME_SERVICES))
	return 0;

	if (!efivars_kobject())
	return 0;

	if (efivars_pstore_disable)
	return 0;

	efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
	if (!efi_pstore_info.buf)
	return -ENOMEM;

	efi_pstore_info.bufsize = 1024;
	spin_lock_init(&efi_pstore_info.buf_lock);

	if (pstore_register(&efi_pstore_info)) {
	kfree(efi_pstore_info.buf);
	efi_pstore_info.buf = NULL;
	efi_pstore_info.bufsize = 0;
	}

	return 0;
	}

	static __exit void efivars_pstore_exit(void)
	{
	if (!efi_pstore_info.bufsize)
	return;

	pstore_unregister(&efi_pstore_info);
	kfree(efi_pstore_info.buf);
	efi_pstore_info.buf = NULL;
	efi_pstore_info.bufsize = 0;
	}

	module_init(efivars_pstore_init);
	module_exit(efivars_pstore_exit);

	MODULE_DESCRIPTION("EFI variable backend for pstore");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:efivars");